Hi,
I have a board and I placed on it a PIC programmed to output 255 on LEDs. When the power supply for the PIC is coming from the EB006-30-5 multiprogrammer things seems to be fine, what I mean: when I set low(ground) the MCLR pin of the PIC in order to reset it the LEDs while are on they dimm a little bit and when I set the MCLR pin to +5v again the LEDs are correctly illuminated and the PIC succesfully is reset.
Now the problem comes when I supply the PIC with power from an other source, if I set the MCLR pin to ground then the LEDs completely go off and when I set again the MCLR pin to +5v the LEDs never light up and the PIC does not work, only if I take the power cord off the board and put it in again.
Can you tell me why this is happening?
The only difference from the power source of the multiprogrammer and the other source is that the multiprogrammer supplies exactly 5v and I think up to 250mA, in contrast the other source that supplies 5.5v and can give up to 2A.
Also do I have to do anything else on my circuits in order to protect the PICs from "burning" or damaging?
Do I have to put also a diode on the +5v line?
Also on pins Avdd and Avss do I have to put power supply?
It seems that after I test the PICs and are working, for examble I estamblish an RS232 communication between two PICs; after some(20) tests the PIC are required to re-programmed or even not working at all(damaged)!!!
Thanks in advance,
Best Regards,
Achillis.
Connections on PIC
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Benj
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Re: Connections on PIC
Hello Achillis
Sounds like a voltage stability problem. Try adding capacitors near the PICmicro to allow it to power up correctly. Add the capacitors between the 5V suppy and Ground as near to the chip as possible. I would use one or two 0.1uf cermaic caps and one or two 100uf electrolytic caps. For my PICmicro driven CNC to work correctly I had to add an extra large 250uF cap right next to the chip as well as the other capacitor values to stop the high current stepper motors from resetting the chip. Maybe also look at the expert configuration settings in PPP or Flowcode as it may be the brownout or power up timer that is adding to your startup problems.
To avoid damagine I/O pins I would always connect through at least a 220 ohm resistor. This way even if two output pins are connected together pulling in different directions the resistor will limit the current between the voltage potentials.
+5v and Ground should be connected directly but the MCLR pin should have a 1K between itself and the 5V supply. You could also add a cap between the MCLR and ground to slow down the startup speed and eliminate the possibility of bouncing startups.
AVdd and AVss should only be connected to 5V and Ground if you have configure the pins to be used as such in the software.
Sounds like a voltage stability problem. Try adding capacitors near the PICmicro to allow it to power up correctly. Add the capacitors between the 5V suppy and Ground as near to the chip as possible. I would use one or two 0.1uf cermaic caps and one or two 100uf electrolytic caps. For my PICmicro driven CNC to work correctly I had to add an extra large 250uF cap right next to the chip as well as the other capacitor values to stop the high current stepper motors from resetting the chip. Maybe also look at the expert configuration settings in PPP or Flowcode as it may be the brownout or power up timer that is adding to your startup problems.
To avoid damagine I/O pins I would always connect through at least a 220 ohm resistor. This way even if two output pins are connected together pulling in different directions the resistor will limit the current between the voltage potentials.
+5v and Ground should be connected directly but the MCLR pin should have a 1K between itself and the 5V supply. You could also add a cap between the MCLR and ground to slow down the startup speed and eliminate the possibility of bouncing startups.
AVdd and AVss should only be connected to 5V and Ground if you have configure the pins to be used as such in the software.
Regards Ben Rowland - MatrixTSL
Flowcode Product Page - Flowcode Help Wiki - Flowcode Examples - Flowcode Blog - Flowcode Course - My YouTube Channel
Flowcode Product Page - Flowcode Help Wiki - Flowcode Examples - Flowcode Blog - Flowcode Course - My YouTube Channel
Re: Connections on PIC
Thanks a lot Ben, I am going to try that .
Allow me to say that I did not quite understand the capacitor value you wrote: uf, did you mean to write nf? for nanofarand?
Also regarding the PICmicro driven CNC, again I did not understand the term CNC but maybe it does not make any difference if I knew!!!!
Ben, from those you wrote if I got it right, I should place the caps in parallel with the power supply?
Or in series?
Again thank you a lot Ben about the help and I will try that as soon as I manage.
Best Regards,
Achillis.
Allow me to say that I did not quite understand the capacitor value you wrote: uf, did you mean to write nf? for nanofarand?
Also regarding the PICmicro driven CNC, again I did not understand the term CNC but maybe it does not make any difference if I knew!!!!
Ben, from those you wrote if I got it right, I should place the caps in parallel with the power supply?
Or in series?
Again thank you a lot Ben about the help and I will try that as soon as I manage.
Best Regards,
Achillis.
-
Benj
- Matrix Staff
- Posts: 15312
- Joined: Mon Oct 16, 2006 10:48 am
- Location: Matrix TS Ltd
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- Contact:
Re: Connections on PIC
Hello Achillis
The 0.1uf cap is the same as a 100nf capacitor, you should be able to get this value easily in a ceramic package. The 100uf capacitors are electrolytic type and are therefore have a much higher capacitance value.
The caps should all be in parallel. Look at the schematic for our Multiprogrammer or Dev board if you are unsure.
CNC - Computer Navigated Cutter
The 0.1uf cap is the same as a 100nf capacitor, you should be able to get this value easily in a ceramic package. The 100uf capacitors are electrolytic type and are therefore have a much higher capacitance value.
The caps should all be in parallel. Look at the schematic for our Multiprogrammer or Dev board if you are unsure.
CNC - Computer Navigated Cutter
Regards Ben Rowland - MatrixTSL
Flowcode Product Page - Flowcode Help Wiki - Flowcode Examples - Flowcode Blog - Flowcode Course - My YouTube Channel
Flowcode Product Page - Flowcode Help Wiki - Flowcode Examples - Flowcode Blog - Flowcode Course - My YouTube Channel
Re: Connections on PIC
Hi Ben,
Thanks for your valuable posts, full of knowledge and very clear to understand. I want to correct one thing if you do not mind pls. CNC= Computer Numerical Control.
This is my first post, on this forum and i really like the FlowCode archetecture. I have just ordered QL-2006 programmer for PIC. Previously i was doing programming with AVR. As i am doing woodworking with my homemade CNC and also made the Laser scanner hardware you can see on my following blogs:
www.my-woodcarving.blogspot.com
www.free3dscans.blogspot.com
I almost read all the posts and soon start a new thread on graphical fountain programming. it will be really interesting one.
Regards
Thanks for your valuable posts, full of knowledge and very clear to understand. I want to correct one thing if you do not mind pls. CNC= Computer Numerical Control.
This is my first post, on this forum and i really like the FlowCode archetecture. I have just ordered QL-2006 programmer for PIC. Previously i was doing programming with AVR. As i am doing woodworking with my homemade CNC and also made the Laser scanner hardware you can see on my following blogs:
www.my-woodcarving.blogspot.com
www.free3dscans.blogspot.com
I almost read all the posts and soon start a new thread on graphical fountain programming. it will be really interesting one.
Regards